In order to produce hydrocarbons, a wellbore is drilled through a hydrocarbon-bearing zone in a reservoir. In a cased hole wellbore (as opposed to an open hole wellbore) a tubular casing is positioned and cemented into place in the wellbore, thereby providing a tubular between the subterranean formation and the interior of the cased wellbore. Commonly, a casing is cemented in the upper portion of a wellbore while the lower section remains open hole.
It is typical to “hang” a liner or liner string onto the casing such that the liner supports an extended string of tubular below it. Conventional liner hangers can be used to hang a liner string from a previously set casing. Conventional liner hangers are known in the art and typically have gripping and sealing assemblies which are radially expanded into engagement with the casing. The radial expansion is typically done by mechanical or hydraulic forces, often through manipulation of the tool string or by increasing tubing pressure. Various arrangements of gripping and sealing assemblies can be used.
Expandable liner hangers are used to secure the liner within a previously set casing or liner string. Expandable liner hangers are set by expanding the liner hanger radially outward into gripping and sealing contact with the casing or liner string. For example, expandable liner hangers can be expanded by use of hydraulic pressure to drive an expanding cone, wedge, or “pig,” through the liner hanger. Other methods can be used, such as mechanical swaging, explosive expansion, memory metal expansion, swellable material expansion, electromagnetic force-driven expansion, etc.
It is also common to cement around a liner string after it is positioned in the wellbore. Running cement into the annulus around the liner is performed using conventional circulation methods. The disclosure addresses methods and apparatus for reverse circulation cementing of a liner.
It should be understood by those skilled in the art that the use of directional terms such as above, below, upper, lower, upward, downward and the like are used in relation to the illustrative embodiments as they are depicted in the figures, the upward direction being toward the top of the corresponding figure and the downward direction being toward the bottom of the corresponding figure. Where this is not the case and a term is being used to indicate a required orientation, the Specification will state or make such clear.